Partial CO2 capture simulation and cost estimation

Master thesis

Åpne

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Sammendrag

Simulation of CO2 absorption using amine solutions have been performed for many years at University College of Southeast Norway, both with and without vapor recompression.

In this thesis, partial CO2 capture was evaluated with a constant heat amount available and a specified exhaust flow. Full-flow (treating all the exhaust) and part-flow (treating only a part) alternatives were simulated with Aspen HYSYS and cost estimated. A standard process and a vapor compression configuration were calculated. The absorption column height varied between 5 and 15 stages (estimated to 1 meter each).

These results show that a standard full-flow CO2 capture process with a 5-stage absorption column gives the lowest cost at 21 NOK/ton CO2 removed over a 25-year period. However, a full flow-vapor recompression alternative increased the captured amount of CO2 considerably while increasing capture cost to 28 NOK/ton CO2.They also show that a vapor recompression CO2 capture process with 15 stages in the absorption column is the most energy optimum at 2.88 MJ/kg CO2 removed, and gives the highest removal rate at 48 %.

A sensitivity analysis of both packing and compressor cost show that with an increased cost, the standard process would still give the lowest NOK/ton CO2. The same was done by setting a price of 0.2 NOK/kW on the recovered waste heat from the plant, here the vapor recompression case gave the lowest NOK/ton CO2.

To be more certain about the conclusions in this thesis, further calculations related to costs not included in this report must be performed, e.g. costs like the transport related to a full-flow or partial-flow capture process.